In various circuit applications, the voltage of a signal is used to represent or convey information. Typically, a digital signal has a voltage at a first level when the signal represents a first state, and the signal has a voltage at a second level corresponding to a second state. For example, a voltage such as 0 V (or another relatively “low” voltage) is often chosen as a ground or reference voltage to represent a logical ‘low’ value or state, and a positive voltage such as 5 V is often chosen as a power supply voltage to represent a logical ‘high’ value or state. The specific voltage levels used, and thus the voltage swing, are often design considerations that are based on a variety of factors, including hardware constraints, resource consumption requirements, and manufacturing or processing constraints.
In some situations, a signal that has a relatively large difference between low and high voltage values is difficult to process with components that are not designed to handle such high voltage swing or that cannot sustain such high-voltage stressing over time. For example, digital circuit components in an integrated circuit often have a relatively low safe operating voltage due to the use of single gate oxide devices. A high voltage signal (e.g., 5 V digital input signal) can cause damage if it is used with digital circuitry that that has a lower safe operating voltage (e.g., 2.8 V).